Happy new year Jamin'. Welcome to the wonderful world of storm damage. We've lost clients as well. It is not the norm so don't base your normal practices on it. When you become a national or international corporation with billions in business then have a clause for every outcome. Take a look at the sales contract for a vehicle, it has all that "fine print" because the likelihood of the event occurring is pretty good. For us it's not.
We don't have a cancellation fee or even a written contract other than our estimate. No signature is required, no legal language cluttering it. Do we have issues arise, sure. From time to time something will happen that gives rise to a desire to somehow prevent it. However, after some careful consideration it really doesn't matter. What it does effect is how we qualify clients and whom we do business with. As DJM pointed out a PIA during the sale will likely be a PIA throughout the relationship.
A contract is a "meeting of the minds" or more specifically,"An agreement between two or more competent parties in which an offer is made and accepted, and each party benefits. The agreement can be formal, informal, written, oral or just plain understood." (from the Lectric Law Library).
While we may have a contract it is the enforcing of it that is problematic. During extraordinary events such as storm damage work expect to lose some. The cost of enforcing contracts is usually too great relative to the gains.